Carburetor



NOV. 14, 1933. E. CHANDLER 1,935,350

. CARBURETOR Filed July 22, 1930 I N V EN TOR. /7/L m/v 5010/1/04 5/? A TTORNEY Patented Nov. 14, 1 933 UNITED STATES PATENT OFFICE CARBURETOR Application July 22, 1930. Serial No. 469,720

6 Claims.

This invention relates to carburetors and more particularly has reference to idling control devices therefor.

In the current plain tube carburetors, the

5 main jet fails to deliver fuel at suction heads of below about three-eighths inch, which corresponds in some recent automobiles to twenty to twenty-eight miles per hour and a throttle crack of .005 to .008". Efforts have been made to maintain the proper mixture proportion below these speeds and throttle openings by special idling feeds comprising one or' more jets at the edge of the butterfly throttle valve when same is in closed position. The chief difficulty with such an arrangement is the great care and precision required in both the location of the auxiliary jet orifices and the fit of the butterfly throttle valve in the throat of the carburetor. If either of these is not held to a very narrow tolerance, it

greatly aifects the control of the idling mixture proportions. Moreover; even if the auxiliary jet orifice is precisely and correctly located and the fit of the throttle is perfect when the carburetor leaves the factory, wear and tear in use may destroy these adjustments and necessitates some sort of readjusting means, all of which adds to the expense of the carburetor and the difficulty of operation.

In order to avoid the foregoing difliculties and to secure a close and reliable control of the mixture proportion at speeds below the functioning of the main jet, I provide a small auxiliary carburetor, in parallel with the main carburetor, with a throttle valve so interconnected with the main throttle valve as to have the proper lead and correlated movements therewith.

An object of my invention is to provide an idling mixture control device which does not depend upon an exact fit of the main throttle and a precise location of an auxiliary jet orifice with reference to the main throttle.

Another object of my invention is to provide an idling mixture control device which is independent of the exact location of the main throttle.

Another object of my invention is to, provide an idling mixture control device which will automatically mix fuel and air in proper proportion,

for idling speeds, in accordance with the air passing therethrough and without reference to the main throttle.

With these and other objects in view which may be incident to my improvements, my invention consists in the combination and arrangement of elements hereinafter described and illustrated in the accompanying drawing, in which:

Figure 1 is a vertical longitudinal section (somewhat diagrammatic) of a carburetor embodying my improved idling mixture control device;

Figure 2 is a fragmentary view of the main and auxiliary throttles, showing. their interconnecting mechanism, with the main throttle in a closed position; and

Figure 3 is a view similar to Figure 2, but showing the main throttle in an open position.

Referring particularly to Figure 1 of the drawing, the numeral 1 denotes the body of a carburetor of the down-draft type which I have chosen for the purpose of illustrating my invention, although, obviously it may be equally well applied to up-draft and other forms of carburetors. Body 1 has a mixing chamber 2 in which are located the usual Venturi throat 3 and butterfly throttle valve 4, which is mounted upon a shaft 5 journaled in the walls of body 1. On the outside of the body 1, there is fixedly mounted upon shaft 5 an operating arm 6 and a lug 7, to which latter is attached a spring 8 anchored at its other end to the wall of the body 1. Located in the Venturi throat 3 is a main jet 9 fed from float chamber 10 through a metering restriction 11 and passageway 12. Air is bled into passageway 12 through bore 13 and metering restriction 14 when the suction on the main jet lowers the liquid fuel from its static level X-X to a point below the junction of bore 13 with passageway 12. 5

Communicating with passageway 12 at a point below the lowest fuel level is an inclined passageway 15.which terminates at its upper end in a vertical bore 16 normally closed at its top by a plug 17. At its lower end, bore 16 communicates through a horizontal bore 18 with a nozzle 19 held in place by a screw plug 20.

My idling mixture control device consists of a miniature carburetor comprising a body 21 fixedly attached to the side wall of the main carburetor body 1, so that its inlet port 22 and out let port 23 register with passages 24 and 25 in body 1, as clearly shown in Figure 1.

Within the body 21 is a longitudinal bore 26' which constitutes an auxiliary mixing chamber and contains a small Venturi tube 27 through which the idling mixture is metered. At the junction of bores 23 and 26 is a transverse bore 28 in which is rotatably mounted an auxiliary rotary throttle Valve 29 which controls the flow of idling mixture. Fixedly mounted on one end of valve 29 are two arms 30 and 31, the former being operated by the usual acceleration pedal connection (not shown), while the latter is connected through a link 32 and arm 6 with the main throtmain carburetor.

tle 4. Link 32 has in its end nearest throttle 4, a slot 33 in which rides a pin 34 fixed toarm 6 so that as the rotary valve 29 moves from its partially restricted position (Figure '1) to its most open position (Figure 2) through an angle of about 18,there is no movement of the main throttle 4. When, however, the valve 29 is further rotated in a clockwise direction to its fully closed position, the main throttle is opened as shown in Figure 3.

The operation of my device is apparent from the foregoing description. With the main throttle closed, as in Figure 1, all the air entering the chamber 2 passes through the auxiliary carburetor and causes a suction to be exerted on the small nozzle 19. This lifts the fuel up passageway 15 until it flows down bore 16 and sprays out of nozzle 19, in accordance with the passage of air through small venturi 27. The size and proportions of the nozzle 19 and venturi 27 of the auxiliary carburetor are such as to maintain proper mixture proportions at all idling speeds.

The lowest idling speed is determined by the opening in the rotary throttle valve 29, when in the position shown in Figure 1. This openlng may obviously be made any size desired by fixing -the position of arm 30 by any suitable means,

such as with a lug or stop screw (not shown) To speed up the engine, arm 30 is moved in a clockwise direction until it reaches the position shown in Figure 2. During this movement the auxiliary throttle valve 29 has been gradually opened, but the main throttle valve 4 has remained closed. Further movement of arm 30 in a clockwise direction now gradually closes auxiliary throttle 29 and opens main throttle 4, as shown in Figure 3. Now no mixture passes through the auxiliary carburetor and all passes through the It will be further noted that the total flow through the main and auxiliary carburetors, no matter what fractions pass through each, is controlled by main venturi 3 and metering orifice 11. Change of idling delivery, therefore, does not interfere with the normal metering of air or fuel through the main jet and Venturi system.

While I am aware. that it has been proposed, as one way of getting control of the mixture in the idling range, to provide a separate air passage and throttle for idling, no one has as yet devised an auxiliary miniature carburetor with a separate throttle for idling and slow speed work, wherein the fuel feed is taken from the main fuel passageway beyond the point of metering (restriction 11) and the air is similarly taken from the main air channel beyond the point of metering (venturi), so that there is no interferenceJwith the normal metering of either air or fuel through the main jet and Venturi system.

While I have herein shown and described one form of my invention, I desire it to be understood that various modifications may be made therein without departing from the spirit of my invention or exceeding the scope of the appended claims.

I claim: 1. In a carburetor having a main throttle, an idling mixture control device comprising a miniature carburetor having an auxiliary throttle and common actuating means for both said throttles including a lost motion connection so arranged thatby manipulation of the actuating means said auxiliary throttle can be opened without opening said main throttle but cannot be closed without changing the position of said main throttle.

2. In a downdraft carburetor having a main throttle and a main jet, an idling mixture device comprising an auxiliary passageway, a Venturi throat in said passageway, a separate throttle for said passageway, a separate fuel jet in said passageway, and a common metering restriction controlling the flow of fuel to both said jets.

3. In a plain'tube carburetor having a mixture passageway, a main throttle and a main fuel nozzle in said passageway, an idling mixture device comprising a conduit leading from said passageway between the fuel nozzle and throttle and bypassing the throttle, an idling fuel nozzle in said conduit, a valve controlling the rate of flow through said conduit, common means for suc cessively opening the valve and the throttle, and a common metering restriction controlling the flow of fuel to both nozzles.

4. In a carburetor having two mixture passageways arranged in parallel, a throttle valve in each passageway, and common control means for the throttles comprising a manually operated member and a lost motion connection whereby continued movement of the manually operated member in one direction first opens one throttle, then gradually closes it while gradually opening the other throttle, and finally fully opens said other throttle.

5. In a plain tube carburetor, a main induction passageway having a main venturi and a throttle therein, an auxiliary induction passageway leading from a point between the restricted zone of the venturi and the throttle to a point posterior to the throttle and having a throttle therein, a fuel nozzle in each of said induction passageways, a common metering restriction controlling the fiow of fuel .to both nozzles, and common means for operating both of said throttles in timed relation.

' 2 6. In a plain tube carburetor, an induction pas- 1 5 sage comprising a mixing chamber and a venturi connected to the mixing chamber and metering the entire flow of air thereto, a throttle controlling said induction passage, an idling mixture device comprising a conduit leading from said induction passage posterior to the most restricted zone of the venturi and by-passing the throttle, a yalve controlling the flow through said conduit, and common manually actuated means for operating said throttle and said valve in timed relation.

MILTON E. CHANDLER. 

